Well, this is only partially true, it will display in the previous output box, but not in the player's chat.
In case your wondering, my commandBlockOutput gamerule was set to true.
UPDATE: this also doesn't work with the /execute command which makes the bug more puzzling as /execute is meant to run the command as if it had been run by the entity specified in the /execute <playername>
Comments 6
Running commands in command blocks should not spam players with messages. A tellraw command and the scoreboard can be used to get the described behavior.
it doesnt spam the player if commandBlockOutput or sendCommandFeedback are false though, because command blocks really spam when those gamerules are true
Yeah bugs don't exactly make sense, just do the following: run the /worldborder get command in a command block and look at your chat, how much do you bet you won't see any success message.